In recent years, with the increasing size of networks, the power consumption of network devices in telecommunication carriers has been increasing year by year. With the goal of reducing this power consumption, the following study has been conducted. In this study, the resources of an entire network are reallocated, thereby intentionally creating an unused route. Then, the power consumption of network devices may be reduced by turning off the power of the network device on the unused route. A target technology of this study has been under development for practical use. Note that a segment on a route in which a network device is in an off state will be hereinafter also referred to as a “power-saving segment.”
Moreover, with the expansion of networks, the complexity of path management has increased. As a method for reducing the complexity, a technology related to automatic path route selection and path generation using various network topologies is used. Examples of the various network topologies include generalized multi-protocol label switching (GMPLS), open shortest path first (OSPF), and open systems interconnection (OSI).
The power-saving segment is recognized as a normal state in a network topology.
FIG. 1A is a diagram illustrating an example of a connection state of an actual network, and FIG. 1B is a diagram illustrating an example of a connection state of a network in a network topology. As illustrated in FIG. 1A, for example, powers of respective interface (IF) boards of a network device #C and a network device #D are in an off state, and the network device #C and the network device #D are actually disconnected. However, even in this state, as illustrated in FIG. 1B, on the network topology, it is recognized that the network device #C and the network device #D are connected. Therefore, the power-saving segment is also a target route which may be selected by a route determination device. However, if the power-saving segment is selected as a transmission route, power of a network device in the power-saving segment is turned on, and therefore, power saving may not be achieved.
There has been proposed a technology for minimizing the probability of selection of a power-saving segment as a transmission route. In this technology, the concept of cost is introduced and a cost value is added to routes between network devices in a network topology. For the power-saving segment, a high cost value is set. Thus, a route with low cost is preferentially selected, and accordingly, the probability of selection of the power-saving segment as a transmission route may be decreased.
Note that a network includes, in addition to a plurality of network devices (nodes), a monitoring control device that monitors a state of the network.
FIGS. 2A and 2B are diagrams each illustrating a method for monitoring a network by a monitoring control device. A first example of the method for monitoring a network by the monitoring control device is “inband signaling” in which the monitoring control device is connected to one of a plurality of network devices via a local connection network (LCN), as a control link, and is connected to the other devices of the plurality of network devices via the one of the plurality of network devices (see FIG. 2A). A second example of the method for monitoring a network by the monitoring control device is “outband signaling” in which the monitoring control device is connected to each of the plurality of network devices via an LCN in one-to-one correspondence, as a control link (see FIG. 2B). In the examples, the LCN is, for example, a local area network (LAN). The above-described route determination device may be the monitoring control device, or the network device to which the monitoring control device is connected.
Japanese Laid-open Patent Publication No. 2009-100442 is an example of the related art.